A motor that includes three brushes, which are a common brush, a low-speed drive brush, and a high-speed drive brush, and is driven at two speeds, a low-speed and a high-speed, is used to drive a vehicle wiper in the prior art. Patent literature 1 describes an example of a motor including two magnets, which are fixed to an inner circumferential surface of a yoke housing, and an armature, which is rotatably arranged at an inner side of the two magnets. The armature includes a rotation shaft, which is supported by the yoke housing, an armature core, which is fixed to the rotation shaft and has a plurality of coils wound thereon, and a commutator, which is also fixed to the rotation shaft. The commutator includes a plurality of segments arranged on the outer circumferential surface of the commutator along a circumferential direction. A common brush, a low-speed drive brush, and a high-speed drive brush are arranged near the commutator. Each brush has a distal portion slidably pressed against the outer circumferential surface of the commutator. The common brush and the low-speed drive brush are arranged at an interval of 180° in the circumferential direction of the commutator. The high-speed drive brush is arranged at a position shifted from the low-speed drive brush by a predetermined angle in the circumferential direction. The armature rotates at a low speed when supplied with current via the common brush and the low-speed drive brush and rotates at a high speed when supplied with current via the common brush and the high-speed drive brush.
Patent literature 2 also describes such a motor including three brushes. The publication describes that the motor can be miniaturized by using magnets forming four or more poles. The motor described in the publication includes four magnets, which are fixed to an inner circumferential surface of a yoke housing, and an armature, which is rotatably arranged at an inner side of the magnets. An armature core including sixteen teeth, which extend radially, and a commutator, which has sixteen segments arranged in the circumferential direction, are fixed to the rotation shaft of the armature. Sixteen coils are wound in an overlapping manner around the armature core. In each pair of segments arranged at a 180° interval, the segments are short-circuited so that they have the same potential in the commutator.